An XA transaction progresses through the following states:
Use
XA START
to start an XA transaction and put it in theACTIVE
state.For an
ACTIVE
XA transaction, issue the SQL statements that make up the transaction, and then issue anXA END
statement.XA END
puts the transaction in theIDLE
state.For an
IDLE
XA transaction, you can issue either anXA PREPARE
statement or anXA COMMIT ... ONE PHASE
statement:XA PREPARE
puts the transaction in thePREPARED
state. AnXA RECOVER
statement at this point will include the transaction'sxid
value in its output, becauseXA RECOVER
lists all XA transactions that are in thePREPARED
state.XA COMMIT ... ONE PHASE
prepares and commits the transaction. Thexid
value will not be listed byXA RECOVER
because the transaction terminates.
For a
PREPARED
XA transaction, you can issue anXA COMMIT
statement to commit and terminate the transaction, orXA ROLLBACK
to roll back and terminate the transaction.
Here is a simple XA transaction that inserts a row into a table as part of a global transaction:
mysql>XA START 'xatest';
Query OK, 0 rows affected (0.00 sec) mysql>INSERT INTO mytable (i) VALUES(10);
Query OK, 1 row affected (0.04 sec) mysql>XA END 'xatest';
Query OK, 0 rows affected (0.00 sec) mysql>XA PREPARE 'xatest';
Query OK, 0 rows affected (0.00 sec) mysql>XA COMMIT 'xatest';
Query OK, 0 rows affected (0.00 sec)
Within the context of a given client connection, XA transactions
and local (non-XA) transactions are mutually exclusive. For
example, if XA
START
has been issued to begin an XA transaction, a
local transaction cannot be started until the XA transaction has
been committed or rolled back. Conversely, if a local
transaction has been started with
START
TRANSACTION
, no XA statements can be used until the
transaction has been committed or rolled back.
Note that if an XA transaction is in the
ACTIVE
state, you cannot issue any statements
that cause an implicit commit. That would violate the XA
contract because you could not roll back the XA transaction. You
will receive the following error if you try to execute such a
statement:
ERROR 1399 (XAE07): XAER_RMFAIL: The command cannot be executed when global transaction is in the ACTIVE state
Statements to which the preceding remark applies are listed at Section 12.3.3, “Statements That Cause an Implicit Commit”.